assume cs:code

code segment
start:
        ;显示 a-z每次停久一点
        mov ax,0b800h
        mov ds,ax
        mov bx,12*160+35*2

        ;显示

        mov al,'a'
        mov cx,26
        xianshi:
        mov ds:[bx],al

        ;等待
        call dengdai
        inc al

        loop xianshi

        mov ax,4c00h
        int 21h

        dengdai:
        push ax
        push dx

        mov dx,1h
        mov ax,0
        xunhuan:
        sub ax,1
        sbb dx,0
        cmp ax,0
        jne xunhuan
        cmp dx,0
        jne xunhuan

        pop dx
        pop ax

        ret


        
        

code ends

end start
